Na la Ra.....
hi kavya, I felt it is common for every kid who's mother tongue is Kannada.... bcz my mother tongue is Kannada... as you said many kids do not use Na ,la , Ra and some more letters bcz it is difficult letters for them to use and also those letters needs lil tougue twistinv technique hence instead of those they pick the easy letter .....nothing to worry... teach your son nicely about the usage of those letters .. do not ever scold or demotivate or discourage ... this is learning period and kids pick it up fast if you train properly and differently....

Kavya it happens when child belongs to a multilingual family. he gets confused and does mistakes. don't get disheartened. u can continue speaking to him in kannada only. if he does a mistake ,just repeat his sentence correctly without scolding or telling him u always speak incorrectly as this could demotivate the child. he might start developing a dislike for this language and thereby avoid using it too. so be patient with him and praise him when he speaks correctly.